This card earns its place through dedicated collector interest, proving that focused demand can sustain strong market value
Voltron decks, where stacking a bunch of powerful buffs on one creature Mutate from 2020s Ikoria comes to mind gain another valuable attacker that can plus card advantage, which can then feed Mondos own protection effect
Tattermunge Maniac has been rather overshadowed by Rakdos Cackler and Dryad Militant
A third Gandalf the White causes abilities to trigger four times, a fourth causes abilities to trigger five times, and so on
One other subtle strength here is the degree of control you can have over exactly when cards are milled, and how many (assuming you have painlands or other unrestricted self-damage sources)
You cast any of the exiled cards you wish to cast for free while this scheme's ability is resolving